A spokesman for Mr Gallacher said the term used to describe the police had become a slang Arabic term used to describe non-believers.

Mr Gallacher said laws preventing the use of a mobile to call or text others to incite a riot failed to cover social networking sites such as Facebook.

"I don't think it is an intentional move by people to get around the law -- it is the way a lot of younger people contact one another and it would appear there is a loophole in the law," he said.

"Using Facebook and Twitter and modern technology gives a quicker way of getting messages out to a larger number of people."

Detective Chief Superintendent Ken McKay said the Middle Eastern organised crime squad was looking into phone communication and would expand the investigation to Facebook.

He said regardless of the laws covering the means of communication, the police could still identify and pursue those responsible for Facebook messages.

"If you incite a riot it doesn't matter by which means, how you do that is somewhat irrelevant," Supt McKay said.

And he said he was concerned by the general lack of respect young people from all backgrounds have for authority.

Meanwhile, a spokesman for Attorney-General John Hatzistergos also said current laws could be applied, adding: "There is a range of serious offences where people call on others to riot or commit other offences via mobile phone or the internet."